1. Field of the Invention
The present invention relates generally to a data processing system for implementing service processing in accordance with a functionally hierarchized software group while executing the processing for communication with a plurality of terminals connected to the system. The present invention relates more particularly to a data processing system capable of, when the terminal connected is changed, dynamically changing definition parameters required by each set of software in accordance with a simple construction without causing an out-of-synchronism state between respective sets of software.
2. Description of the Related Art
A data processing system implements the service processing in accordance with the functionally hierarchized software group while executing the communication processing for performing communication with the plurality of terminals connected to the system. This data processing system has such a construction that the data needed by the software for controlling the terminal are expanded in the form of definition parameters on a main memory. That is, this data processing system implements the service processing while executing the communication processing for effecting the communication with the terminals in accordance with these definition parameters.
In this type of data processing system, for enhancing a guaranty of an operating schedule and a communication performance, the definition parameters for all sets of software are expanded on the main memory when starting the system, and the communication are carried out. Accordingly, if the terminal as a destination for communication is changed, it is required that the data about the changed terminal is modified by updating the definition parameters expanded on the main memory. This change of the terminal could be as a result of adding connection of a new terminal, changing the type of an already-connected terminal, or disconnecting a (deletion) of the already-connected terminal.
There arise, however, the following problems inherent in updating the definition parameters.
For instance, there exists a construction to take such an arrangement that the definition parameters are re-expanded for updating the definition parameters when changing the connected terminal. If constructed in this way, it follows that the definition parameters of unchanged terminals are also temporarily deleted on the occasion of re-expanding the definition parameters. Hence, it follows that the system is temporarily stopped with the updating of the definition parameters.
Further, the data processing system has, as a software group for implementing the service processing, sets of software offered by a software maker such as a communication access method, a DB monitor (an on-line transaction monitor for accessing to a database), a DC monitor (an on-line transaction monitor for executing data communication) and also application programs developed by users. These sets of software are mutually functionally hierarchized. Accordingly, there exists a possibility in which an out-of-synchronism state is caused between the respective sets of software. The "out-of-synchronism state" termed herein is a state where a parameter definition in the software of another hierarchy is, although the parameter definition in the software of one hierarchy has been modified, not yet modified, and hence the service can not be implemented. In general, the software offered by the software maker is capable of taking the synchronism with other software offered by the same maker with measures taken by this software maker. The definition parameters possessed by the software developed by the user would be original different from the definition parameters possessed by the software offered by the maker. For this reason, with the updating of the definition parameters, there is a possibility in which the out-of-synchronism state will be produced between the software developed by the user and the software offered by the software maker and between sets of software developed by the users.
For dealing with the problems given above, the conventional data processing system has hitherto adopted such a method that all the terminals which would be destinations for communication are defined beforehand, and the definition parameters corresponding thereto are previously expanded on the main memory. Further, in some cases, the conventional data processing system has taken such a method that the definition parameters are concentratedly managed by a network directory, and each software reads the concentratedly managed definition parameters. The conventional data processing system thus makes unnecessary the updating of the definition parameters.
If a data processing system conforms with the pre-definition method as in the former case, however, each software inquiries an unsubstantial communication destination terminal which is previously defined but not yet connected to the data processing system. Therefore, a problem is caused, wherein a futility is produced in the communication. Further, the terminals are further added, and consequently all the pre-definitions made beforehand are used up (i.e., all the pre-defined terminals are actually connected to the data processing system). In this case, there arises a necessity for effecting the pre-definition once again. This therefore presents such a problem that the system has to be stopped.
Besides, if a data processing system conformed with the method of using the network directory as in the latter case, the system itself increases in size. Moreover, each time the program of the software is executed, the definition parameters are read from this network directory, resulting in a deterioration in terms of performance. A cashing process (a reading process such as periodic reading) is therefore required. Accordingly, the problem is that the system processing becomes complicated.